Baseball is a team sport, popular in the Americas, East Asia and Australia. In its usual form, the game is between two teams of nine players on a playing field consisting of 4 bases, arranged in a diagonal square ("the diamond") and a large outfield (see fielding positions for a typical layout).

Play of the Game
As the game starts, the home team takes the field, while the visitors come to bat. After making three outs, the visitors take the field and the home team bats.

The basic contest is always between the pitcher, who tries to throw the ball so it cannot be cleanly hit, and the batter, who tries to hit the pitched ball with a rounded bat. If the batter hits a "fair ball" into the field of play, the hitter runs to first base and any of his teammates who are already "on the bases" may attempt to advance to another base. If a baserunner is already on first base, they must try to advance or the batter will be out; no two offensive players may ever stay on the same base. The batting team scores a run[?] by advancing a player all the way around the diamond.

If the ball is caught before it bounces, or the ball is fielded and thrown to a base before a runner arrives there, the player is out, and must return to his team's dugout. The initial decision to make first base 90 feet from home plate was an inspired one; it means that no runner, no matter how fast, can beat the throw to first of a ball cleanly fielded and properly thrown to first by a fielder in proper position. But if the fielder is out of position, or hesitates, or throws wide of the base, the play is often razor-close, and quite exciting.

There is also an imaginary area above "home plate" (where the batter stands) between the batter's knees and chest called the "strike zone". (Actually the "strike zone" varies a good bit depending on the league level of the teams and is relatively frequently re-defined by league rules makers.) Any pitch which passes through this area is a "strike", as is any pitch at which the batter swings and misses. If a batter records 3 strikes before putting the ball in play, he is out - called a strikeout. (An exception is if the third strike evades the catcher but this rarely occurs.) Any pitch which is not a strike is called a Ball. A batter who receives 4 balls from a pitcher may walk to first base and cannot be tagged out. This is called a "walk." A batter may also move to first base if he is struck by a pitched ball, unless he puts himself in the path of the pitch and makes no attempt to avoid being struck. In addition, if a player does make contact with the ball but does not hit a fair ball, this is called a foul ball. Whether a ball hit is fair or foul is defined by two lines, drawn to the side of the diamond, and by two poles, located to the left and the right of the outfield. Also, anytime the player hits the ball backward and it leaves the play area, this is called a foul. Fouls also count as strikes, unless the player has two strikes already when hitting the foul, in which case the player must go at bat for one more turn. If a foul ball is caught by a defensive player before it bounces, then the hitter is out.

After 3 outs (a "half-inning") the roles of the fielding and hitting sides are reversed. Usually, 9 innings are played. The aim of the game is to score more runs than the opposing team. If both teams have scored the same number of runs at the end of 9 innings, an extra inning is added to the game. If the score remains tied, another inning is added. This process repeats until the score is no longer tied at the end of an inning. Thus, the team which hits in the second (or "bottom") half of the inning always has a chance to respond to a run scored by the team batting in the first (or "top") half. As there are tactical advantages to this, the home team is always granted the right to bat in the bottom half of the inning. Baseball games end with tie scores only because of weather or lighting conditions have made it impossible to continue play. In the Major Leagues, games in which the score is tied are not counted towards a team's game total (as technically a tie game is considered as unfinished), although statistics are retained as long as the game is of official regulation (five half innings for each team; only four for the home team if the home team is ahead).

Pitching
Effective pitching is vitally important in baseball. A pitcher who starts games should be able to pitch for six or seven innings before being replaced by specialist relief pitchers, who finish the game off. For a starter to pitch all 9 innings (a "Complete Game") is a personal achievement, though this was not always so -- the average number of innings pitched has been declining slowly in the professional leagues almost since their inception, and 9 innings was once the norm. Pitching is also physically demanding: a modern-day starting pitcher can usually throw 100-110 pitches with no ill effects, but throwing many more reduces effectiveness, and sometimes serious and permament arm injury. In a major league season then, a club usually keeps a cadre of 5 starting pitchers (known as the "starting rotation") to start games, giving pitchers at least 3 or (preferably) 4 or 5 days rest between starts.

Five to seven more pitchers are employed as relief pitchers or relievers, to pitch the innings not handled by the starting rotation. Today, every team tries to employ one of these pitchers as a closer -- that is, a relief pitcher specifically designated to pitch the final inning of a game in which his team is leading, in order to preserve the win.

In order to prevent the batter from hitting the ball well, a good pitcher should be able throw a variety of different pitches, which will usually be a subset of the following basic types.

Fastball: The fastball is the pitch that most pitchers throw most of the time. Some "power" pitchers can throw it 95-100 mph, and rely on this speed to prevent the ball being hit. Others throw more slowly but put movement on the ball or throw it on the outside of the plate where the batter cannot easily reach it. Gripping the ball with the fingers across the wide part of the seam ("four-seam fastball") produces a straight pitch, gripping it across the narrow part ("two-seam fastball") produces a sinking fastball, and holding a two-seam fastball off-centre ("cut fastball") imparts lateral movement to the fastball.

Curve ball: The curve ball is thrown with a hand motion that induces extra rotation on the ball causing it to "break," to fly in a more exaggerated curve than would be expected. The pitch is slower than a fastball, and this difference in velocity also tends to disrupt the hitter's timing. Good curve balls often seem to drop sharply as they reach the plate, making the batter swing above it; but a curve ball which fails to break (a "hanging curve") will be easy meat for a good hitter. A Screwball is similar to a curveball, but thrown from the back of the hand in order to impart opposite rotation and opposite movement.

Slider: A slider is half-way between a curve ball and a fastball, with less break but more speed than the curve. It will tend to drop less and move toward or away from the batter more than a curve. The extra speed can fool the hitter into thinking it's a fastball, until too late. Some pitchers also use a cut fastball (or cutter) which is one step closer than the slider to the fastball on the spectrum between fastballs and curves.

Change Up: A change up is the traditional off-speed pitch (i.e. slower than the fastball), which otherwise resembles a fastball. It is thrown with the same arm action as a fastball; the speed difference is due to a different grip. This (hopefully) causes the hitter to be fooled and swing before the ball arrives. A change up also tends to break slightly in the same direction as a screwball due to the way it is commonly released, this makes it an effective pitch away from the plate.

Knuckleball: Thrown slowly and with a minimum of rotation, the knuckleball (actually thrown off the tips of the fingers) relies on chaotic airflow over the stitched seams of the baseball to produce an erratic, unpredictable motion. This makes it hard to hit, hard to catch and hard to aim, and it is consequently not a favorite with catchers and managers.

Split-Fingered Fastball / Forkball: Held between the first two fingers, thrown hard and with a strong downward motion. This pitch tends to tumble downwards and can break in either direction, depending on the release. It can be thrown as hard as 90 mph, so it can look like a fastball until it breaks near the plate. Most effective when thrown in the lower part of the strike zone.

The pitcher will try to make the batter miss the ball entirely ("go out on strikes") or hit it so that it can be handled by one of the fielders. This generally involves throwing the ball in a way, or to a location, that the batter is not expecting, causing him to hit it weakly or not at all. Since it is very difficult to do this, the batter will often be able to hit the ball strongly. Good fielders may have some idea of where the pitcher is likely to throw the ball, and therefore where the hitter is likely to hit it (an "outside" pitch will generally be hit to the side of the field that the batter faces, for instance), and may be prepared to field the ball there if the batter hits it well.

Batting
The batter tries to hit the ball in such a way that it cannot be cleanly handled by a fielder; good hitters can place the ball where they want with surprising skill. In the early 1900's, place hitting was a high art, and the home run was considered a freakish spectacle. Place-hitting was exemplified by Willie Keeler's axiom, still shouted today: "Hit 'em where they ain't."

In 1919, Babe Ruth broke the standing home run record, and changed fundamentally the way the game was played, becoming a popular sensation in the process. The introduction of regularly changed balls, the new cork-centered balls introduced in 1910 and the banning of tampering with the balls (with spit or by scuffing the surface) made the hitters task easier, and the fresh white balls were easier to see and travelled further, making the home run more likely. It has also been suggested, although there is little evidence, that owners had the baseball "juiced", since this new offensive style was very popular and was helping to redeem the game after it was rocked by gambling scandals. Regardless, ever since, the mighty home run has become the surest way to rouse a crowd. Accordingly, the most common batting style employed today is the free-swinging style of Ruth rather than the place-hitting style of Keeler.

Occasionally, players have been caught using illegally modified corked bats, an action subject to ejection and possible suspension and fines.

The style of play
Baseball has an antique, unhurried pace. Both football and basketball use a clock, and fans must watch games end while one team degrades the competitive element of the game by "killing the clock" rather than competing directly against the opposing team. But baseball has no clock; you cannot win without getting the last man out, and a rally can start at any time.

(In recent decades, observers have criticized baseball for this, with some justification as the time required to play a baseball game has increased steadily through the years. One hundred years ago, games typically took an hour and a half to play; today, four-hour nine-inning games are not uncommon. However, this is primarly due to increased commercial breaks more than a decrease in playing speed. However, increased offense and more pitching changes also prolong the length of the game.)

Baseball is a team game -- even two or three Hall of Fame players cannot guarantee a pennant by themselves. In the last years of the 20th Century, a trend toward building teams based on a more even distribution of talent throughout the lineup became noticeable. The Seattle Mariners and the Florida Marlins were two teams that began moving away from the previous belief in building teams around superstars. Team salary caps led to the decision by many owners to pay more solid players decent money rather than surrounding one or two expensive superstars with a below-average set of teammates. It remains to be seen if this strategy will be successful.

Paradoxically, the game places individual players under great pressure and scrutiny one at a time. The pitcher must make a good pitch or suffer reproach; no one can help him throw the ball. The hitter has a millisecond to swing the bat; no one can help him then; he hits a line drive; the outfielder makes a lonely decision to try to catch it or play it on the bounce. Baseball history is full of heroes and goats -- men who in the heat of the moment distinguished themselves with a timely hit or catch, or an untimely strikeout or error.

It is a beautiful, leisurely game on the surface; but sudden and fierce beneath.

"Of all the silly and sentimental things said about baseball, none is sillier than the description of the game as 'unhurried' or 'leisurely'. Baseball action involves blazing speeds and fractions of seconds, and is as much a mental contest as a physical one. The pace of the action is relentless: There is barely enough time between pitches for all the thinking that is required...."--George F. Will, "Men At Work: The Craft of Baseball"

Baseball IS leisurely -- for the idle observer. That said, no other sport packs so much into so little. The pitch and swing of the bat can, at any time, change the entire game. And how long is that? Less time than it takes a basketball to leave a shooter's hands, much less arc to the basket and clang around. A microsecond compared to the drop-back, plant, pass, catch of a football.

When all is said and done the agony and beauty of sport is measured in inches, and nowhere is this microcosm as perfect as it is on a baseball diamond. Two out, bottom of the ninth. Runners at the corners. Down by two runs. The home field crowd, to a man, on its feet. The windup. The pitch. Less than half a second later the result. The crowd breathes again. Foul. Start all over. No other sport is that cruel. That pure. That measured.

There is a reason that there is no clock in baseball, mere timepieces are insufficient to measure the beats of the game. Leave the clocks to the sports that are slow and lumbering... the seven foot center gallomping to the top of the key, the 250 pound fullback charging the line. These are the sports where a second or five matter. Not in baseball. There the time slice is far too fine to be caught in mere gears. It is an instant that can only be measured in the skip of a heartbeat or the sudden drop in a stomach. It is the interval between jubilation and despair.